Abstract
The United States is unique among nations in having private companies run its health insurance system, handle claims, and make determinations about coverage. Over the past 20 years, American physicians have increasingly felt the effects of competition among these companies to minimize the risks they cover and the claims they pay1. However, the critera for decisions by insurance companies have gone largely unexamined. In this issue of the Journal, new evidence and an inside account shed light on the ways in which insurance companies decide when and when not to pay for costly medical treatments that may benefit very . . .

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